Determine the number of ways to arrange the letters of the word TOOT.
First we count the arrangements if all the letters are unique, which is $4!$. Then since the T's and the O's are not unique, we divide by $2!$ twice for the arrangements of T's and the arrangement of O's, for an answer of $\dfrac{4!}{2! \times 2!} = \boxed{6}$.